1. Field of the Invention
This invention relates to an electronic clinical thermometer. More particularly, the invention relates to an electronic clinical thermometer equipped with a sensing unit which relies upon a temperature sensing element having a non-linear characteristic, wherein the magnitude of an output signal from the sensing unit is capable of being corrected to approximate a linear output value in a predetermined temperature range.
2. Description of the Prior Art
Temperature sensors presently available for practical use almost all have a temperature output characteristic which is non-linear. With tempeerature sensing elements of this kind, it is common practice to obtain a linearized output by using hardware techniques relying upon bridge circuits or the like. Recently, however, systems have been proposed wherein the correction into a linear output is achieved through application of software-based techniques.
In one proposed example, a deviation in the non-linear output value of a thermistor from a linear output value in a predetermined temperature range is corrected by relying upon correction means in which items of linear output data corresponding to each item of non-linear output data from the thermistor are stored beforehand, in the form of a table, in a ROM (read-only memory). In actually measuring temperature, non-linear output data arriving from the thermistor is applied to the correction means as an input signal, in response to which the correct corresponding linear output data is obtained from the ROM. A defect encountered with this system, however, is the requirement for a memory capable of storing a table of great size.
In another example of a proposed electronic clinical thermometer, items of data indicative of the non-linear characteristic are obtained in advance, and an arithmetic program for finding linear output values from the non-linear output values, by means of computations based on said data, is loaded into a microcomputer. In order to obtain linear output values, therefore, it is necessary for the microprocessor to perform complex and time-consuming processing. In other words, the user must wait for the processor to complete its processing operations before the results of measurement can be known.